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CASTO RESERVOIR
Structure dossier · WDID 6303643 · 3 · GILL CREEK · DWR record
Where this page's figures come from
Generated 2026-08-27 21:19 by Hydrohistorian. Sources: DWR HydroBase snapshot HydroBase_CO_20260707 (history) + CDSS REST (current), USGS NWIS cross-checks. Engine v0.5.0 (2deb1d7) — every figure regenerates from this named code version and data image.
Where it sits
Location as DWR records it. Faint dots are the neighbouring water; click any to open it.
Which of its rights are out of priority?
Not computable for this structure: this structure is not on the modelled flow network, so no reference gage can honestly stand in for it.
Where it sits in line
Priority 1903-06-10 — 205th most senior of the 533 structures with decreed rights in this water districtDWR's administrative subdivision of a river basin; the unit calls are usually stated in..
Under prior appropriationColorado's rule for sharing water: first in time, first in right. Age decides, not proximity or need., everything ahead of it in this line is satisfied in full before it receives any water. Immediately ahead: BURG RESERVOIR (1901-08-15). Immediately behind: LONE OAK DITCH (1904-04-01).
Decreed rights (2)
| Admin noDWR's numeric encoding of a water right's seniority. Smaller is more senior; the integer part counts days from 1849-12-31 to the date that ranks the right. | AppropriatedWhen water was first put to beneficial use. It sets seniority unless a prior adjudication date is later. | AdjudicatedWhen the water court confirmed the right. A use decreed in 1975 was not a decreed use in 1955, however old the appropriation is. | AbsoluteA right actually put to use, as opposed to conditional -- a placeholder for a use not yet made. | ConditionalA right reserving a place in line for a use not yet made; it must be diligently pursued or it lapses. | Units | UsesWhat the court said this water may be used for -- irrigation, municipal supply, augmentation and so on. | Case |
|---|---|---|---|---|---|---|---|
| 30079.19518 | 1903-06-10 | 1939-02-11 | 170.6 | 0.0 | A | IRR | 44 |
| 56613.35038 | 1945-12-06 | 2005-12-31 | 811.4 | 0.0 | A | IRRRECFISWLD |
Recorded use (last 15 years on record)
In a median year this structure has a recorded diversion of 180 AF. Its most recent year on record, 2025, came in at 156 AF — 86% of that, and 6th lowest of the 12 years with a recorded volume.
This structure records both diversions and reservoir releases — they are separate water movements and are accounted separately below.
| Year | Diverted (AFA volume: one acre covered a foot deep, about 326,000 gallons -- roughly a suburban household's outdoor use for a year.) | Compared with its own record | Released (AF) | Days recorded | Peak (cfs) |
|---|---|---|---|---|---|
| 2008 | — | no recorded volume | 268 | 0 | — |
| 2009 | — | no recorded volume | 701 | 0 | — |
| 2010 | — | no recorded volume | 359 | 0 | — |
| 2011 | 0 | 1st lowest of 12 · 0% of median | 727 | 4 | 0.0 |
| 2015 | 293 | 10th lowest of 12 · 162% of median | 0 | 217 | 1.6 |
| 2016 | 233 | 9th lowest of 12 · 129% of median | 0 | 186 | 1.6 |
| 2017 | 475 | 11th lowest of 12 · 263% of median | 675 | 176 | 18.0 |
| 2018 | 154 | 5th lowest of 12 · 85% of median | 383 | 236 | 1.1 |
| 2019 | 1,035 | 12th lowest of 12 · 573% of median | 540 | 105 | 7.4 |
| 2020 | 205 | 7th lowest of 12 · 114% of median | 486 | 148 | 1.7 |
| 2021 | 130 | 4th lowest of 12 · 72% of median | 170 | 105 | 1.4 |
| 2022 | 211 | 8th lowest of 12 · 117% of median | 192 | 22 | 8.1 |
| 2023 | 5 | 2nd lowest of 12 · 3% of median | 1,156 | 16 | 0.2 |
| 2024 | 50 | 3rd lowest of 12 · 28% of median | 658 | 61 | 0.4 |
| 2025 | 156 | 6th lowest of 12 · 86% of median | 227 | 304 | 0.7 |
Advisory reading aid on public data — not an administrative or legal conclusion, not a title opinion, and not a substitute for DWR administration or an engineer's analysis. Methodology review status is disclosed at hydrohistorian's basin pages.